old PC fans for seed starting airflow?

[JRinPA]

I've been trying to find some videos or instructions about using old PC case fans for seeds. I have not found much, certainly less than I expected to find. Anybody have a set up using them?

I'm going to set up an old oscillating stand fan for now but that will pull 60-90 watts on low. I have a kill-a-watt meter so will check that. I checked a 20" box fan last summer and low was about 3/4 the wattage of it on high.

[bower]

Sad to say the fans on my computers are the first to go, and the cause of other failures, so I never had one to repurpose.
Never grow peppers in the office. Pepper pollen is deadly.

[JRinPA]

Uh oh, who experienced "death by pollen"?

I did some testing and the fan I have isn't really that bad in the overall scheme of things. Old panasonic, made in Japan, 51 watts on low. The fan will cost about 7.5 cents a day. I think my rate is up to 12 cents now.

Current peak at 385 watts total for the whole 10 tray setup. So about 55 cents a day. With the ridiculous fees, the electric bill is close to $100 with normal winter activity so an extra $16 for a couple months is nothing for the food return, and it won't be at that peak for that long.

I would still like to see some setups though. Lots of old fans here - most are 12v I guess. Maybe some 5v? The stuff on youtube is weighted towards the ridiculous with big arrays...for what purpose, I don't know, maybe solar, maybe just for youtube click/hits.

[Cole_Robbie]

The crypto mining fad is responsible for a lot of them. I like the ones with a dimmer switch for speed control. Led lights don't have fans for their ballasts, but I think it is an improvement. Heat reduces diode life and generally is bad for anything electronic.

[JRinPA]

There was one youtube vid on a soldering station setup, I might well make that. And I have used box fans fcaw for welding, so maybe an array of computer fans running on battery would be useful/portable for that.

[JRinPA]

The fan will cost about 7.5 cents a day. I think my rate is up to 12 cents now.

Current peak at 385 watts total for the whole 10 tray setup. So about 55 cents a day. With the ridiculous fees, the electric bill is close to $100 with normal winter activity so an extra $16 for a couple months is nothing for the food return, and it won't be at that peak for that long.

Uh oh, I found the bill that I couldn't seem to find. The generation actually dropped a bit to 11.3 cents /kwh. But I forgot the distribution fee which is another 4 or 5 cents on its own.

[zeuspaul]

@JRinPA If it makes you feel better I pay 40 cents per kwh.

[slugworth]

Some pc fans are actually 12v vs 120v so you have to be careful wiring them up that you don't smoke up the place.
I use the 120v versions with a mesh over them to prevent amputations of anything that gets withing range.Ouch.

[slugworth]

I put the fan on the same timer as the lights.
So it isn't a constant draft.
I just got done wiring up a couple of 4 inch electrical boxes with outlets and lamp dimmers
so I can use food warming trays for my seeds/cuttings.
The food warming trays are cheap in thrift stores but are way too hot for our use.
I feed them with a reduced voltage from the dimmer to get just the right heat out of them.

[worth1]

I would think an AC fan would be more energy efficient than a DC fan.
The 120 AC has the be reduced to 5 or 12 volts DC or AC or whatever and this is wasted energy.
The DC fan may only draw a certain amount of energy but they don't take into account for the transformer energy loss to get there.
You phone charger draws energy whether the phone is charging or not.
My charger makes a little popping noise when I plug it in.

AC is the way to go and Tesla proved it.

But I could be totally wrong in this application.
But it proved out for me with another project.

[slugworth]

pc fans are free if you have a stack of them already.
12v tyrapped together will even work when the power goes out off a battery.
Used many times here after a hurricane knocks power out for days.

[JRinPA]

I put my onions outside today so I'm back one shelf trays and lights.

For one row of trays I think a single case fan would work. *think*. It would only be a few watts to run. I checked the ratings, 0.12A @12vdc. 0.15A @12vdc, etc. 2-3 watts each. I could use ni-mh rechargeable eneloops. 10- 2400mAh eneloops in series would run a fan 10 hours for a half discharge. But, I have DC timers so I could actually run them for 30 seconds on, 10 minutes off. I have no way to do that with AC. I don't see the need for constant wind, that's where the big loss is with AC for me. Just the fact that it is on all the time instead a few cycles per hour to disturb the plants a little. Plus it dries the tops of the soil blocks out way too much for laggard seeds to germinate. That is what I really hate about the big fan, it dries everything out. I have "remembered" that this past couple weeks.

For the input on the charger's AC adapter is .3A max at 100 -240v. So 110 would be about .3A draw at most. 2400 mah eneloops. 10 eneloops in series for 12v, 4 bay charger, so 2-1/2 charge cycles of 2 hours each. So 5 hours at .3A max draw x 120 vac = 36 wattx5 hours=.18kWh used on a recharging day. And I think that recharge would be once every three weeks, with a 20:1 timer reduction factored in.


When on constantly, the .18kWh recharge would be needed daily. 1/3 the cost but pain in the butt to recharge and a lot less air than the big fan. 3 little case fans would cost the same as the AC fan.
Whereas the AC fan is using 51 watts x 12.5 hours= .64kwh every single day

With timer, should be 20x the longevity, so I figure one recharge every 3 weeks. 1 charge at 1/3 the cost and divided by 21 day is 1/63rd the cost of the big AC fan, to power a single case fan.

Just a matter of whether one case fan is enough to stir some leaves a bit. I already have the batteries, times, and battery holders from duck hunting, this just gives them more use. Otherwise, a steep capital cost.